基于参数扰动的混沌控制方案在Buck-Boost变换器中的应用研究

分布式直流微电网中,直流母线与大电网的接口变换器通常选择具有升、降压功能的DC-DC变换器,如Buck-Boost变换器,来提升或降低光伏阵列或其他储能单元的输出电压,使之与直流母线电压匹配。Buck-Boost变换器作为一个强非线性系统,在输入电压、参考电流等电路参数变化时容易产生分叉、混沌等非预期情况,使变换器性能变差甚至不能正常运行。基于峰值电流控制型Buck-Boost变换器的频闪映射模型,分析了变换器的非线性动力学现象。基于参数扰动的混沌控制原理,设计了一种适用于峰值电流控制型BuckBoost变换器的混沌控制方法 ,该方法可使进入混沌状态的变换器重新回到周期态,并使变换器的稳态性能、输出纹波等得到显著改善。

Applications of Chaotic Control Scheme Based on Parameter-perturbation in Buck-Boost Converter

In the distributed DC microgrids, a DC-DC converter(e.g., Buck-Boost converter) is usually selected as the interface converter between the DC bus and the large power grid, such that the output voltage of PV arrays or other energy storage units can be boosted or lowered to match the DC bus voltage. As a system with strong nonlinearity, some unexpect-ed situations such as bifurcation and chaos will occur when the circuit parameters(i.e., input voltage, reference current, etc) of the Buck-Boost converter change, which degrade the performance of the converter or even result in its failure. In this paper, a strobe mapping model is built based on a peak-current mode controlled Buck-Boost converter, and its nonlinear dynamics characteristics are analyzed. Based on the principle of chaotic control of parameter-perturbation, a chaotic control scheme is designed, which can be applied to the peak-current mode controlled Buck-Boost converter. Under this scheme, the converter operating in a chaotic state can quickly return to a periodic state. Meanwhile, the performances of the converter, like its steady-state behavior and ripples of output voltage, can be improved evidently.